Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2.
DOI: 10.17667/ iim.2016.1-2/15.
DC Mo o Simula ion wi h ARM Based
Ha dwa e in he Loop
Sándo Csikós
Uni e si y o Szeged Facul y o Enginee ing
TechnicalIns i u e
Szeged, Hunga y
[email protected]
Ádám Bálin
Uni e si y o Szeged Facul y o Enginee ing
Technical Ins i u e
Szeged, Hunga y
Abs ac —Ha dwa e in he loop es ing is inc easingly
impo an p oduc es ing o cu ing down ime o ma ke . In
my p e ious a icle I iden i ied he pa ame e s o a DC mo o
con ol sys em using sys em iden i ica ion. An implemen a ion o
he esul ing ans e unc ion was de eloped on an ARM based
ha dwa e in he loop sys em and has been e i ied agains he
o iginal sys em. The esul s show ha he ha dwa e in he loop
sys em p oduces esponses wi hin ole ance o he s imulus
signals and can be used o es ing o con olsys ems.
Keywo ds—Ha dwa e in he loop, LabVIEW, ARM
mic ocon olle
I. INTRODUCTION
Model based design is a me hodology used in designing
and es ing con olle so wa e implemen ed in PLCs o
mic ocon olle s. The h ee phases ha phases o model based
design a e model in he loop (MIL) whe e only he
ma hema ical ep esen a ions o he plan and con ol sys em
a e used, so wa e in he loop (SIL) whe e a simula ed
implemen a ion o he con olle con ols a simula ion o he
plan and ha dwa e in he loop (HIL) whe e a eal con olle
con ols a eal- ime simula ion o a plan . As he las
simula ion s age o p oduc de elopmen ha dwa e in he loop
simula ion is used o cu down es ing ime, ensu e he
co ec ness o he implemen ed con ol algo i hm and
dec ease es ing cos s. As such i is impo an o make he
simula ing de ice be as close o he eal sys em as possible.
Cu en applica ions use eal- ime ope a ing sys ems o ensu e
he high e esh a e needed o such simula ions and a e
usually qui e cos ly such as he dSPACE simula o o he
Na ional Ins umen s PXI sys ems jus o name a ew.
Real- ime compu ing is di ided in o so eal- ime, whe e
he use ulness o a esul deg ades a e i s deadline, i m eal-
ime whe e in equen deadline misses a e ole a ed and ha d
eal- ime whe e missing a deadline is o al sys em ailu e.
Missing deadlines deg ades he sys ems quali y he e o e a
ha d eal- ime simula ion me hod would gi e us he bes
esul s. The e a e nume ous eal- ime simula ions (RTS)
cu en ly in li e a u e [1-6], howe e hese sys ems a e so
eal- ime. Simila esea ch has been conduc ed by [7]
eaching simula ion s ep imes o 250-50 µs wi h a low cos
ha dwa e implemen a ion. In his pape expe imen s we e
concluded o see i a low cos implemen a ion using an ARM
p ocesso could achie e he same esul s o simple sys ems,
hus u he lowe ing he es ing cos o es ing, also p o iding
an oppo uni y o c ea e a sys em o he a e age use . Such a
sys em could also be used in educa ion due o he low p ice
and s ong connec ion o he cu en con ol sys ems cou se
ma e ial being augh a he Uni e si y o Szeged.
The desi ed end esul would be o c ea e a amewo k ha
enables ha d eal- ime ha dwa e in he loop es ing o linea
ime in a ian MIMO sys ems and sys ems wi h nonlinea
cha ac e is ics such as he pneuma ic a i icial muscle (PAM)
since he o he main esea ch opic a he Uni e si y o Szeged
Facul y o Enginee ing is he high accu acy posi ioning o
pneuma ic a i icial muscles o obo ics and ehabili a ion
applica ions [8].
II. METHODOLOGY
The hypo hesis being es ed was ha a 32bi ARM
mic ocon olle could be used o ha d eal- ime ha dwa e in
he loop simula ion. The mic ocon olle chosen was he
STM32F746ZGT6 on he STM32F746 Nucleo boa d (Fig. 1).
Fig. 1. STM32F746 Nucleo boa d
The STM32F746ZGT6 ea u es a 216 MHz ARM
p ocesso wi h a buil in single p ecision loa ing poin uni
enabling ope a ions on numbe s ep esen ed as loa s o be
comple ed unde a couple o cycles depending on he
ope a ion. A loa ing poin uni is o key impo ance as i
will be shown.
The p og amming en i onmen used was he Keil MDK
wi h he STM32CubeMX o pin se up and
ini ializa ion.Measu emen s we e done using LabVIEW, he
Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2.
DOI: 10.17667/ iim.2016.1-2/15.
da a acquisi ion de ice used was a myRIO (Fig. 2) om
Na ional Ins umen s.
Fig. 2. myRIO om Na ional Ins umen s
To es he hypo hesis a physical sys em was cons uc ed
consis ing o a small DC mo o wi h a magne moun ed on he
o a y sha and an AS5145 absolu e magne ic o a y encode
wi h 12 bi s o esolu ion moun ed pe pendicula o he sha
(Fig. 3).
Fig. 3. Sys em o be simula ed.DC mo o wi h magne and AS5145
magne icencode .
The p ocedu e used was he ollowing. Assuming he
model o he sys em o be he one shown on Fig. 4 whe e he
inpu o he sys em is ol age and he ou pu is he o a ional
speed o he sha equa ion (1) and (2) can be de i ed.
Fig. 4. Block diag am o mo o
whe e:
 – ol age di e ence be ween + and - inV
 i– cu en lowing h ough he mo o inA
 R – esis ance o he mo o inΩ
 L – induc ance o he mo o inH
 K – cons an o p opo ionali y inV/ ad/s
 J – ine ia inkgm2
 b – o a ional dampening cons an Nms/ ad

󰇗
– o o speedin ad/s
F om he block diag am equa ion (1) and (2) can be
de i ed.
(1)
(2)
Knowing equa ion (1) and (2) we can apply he Laplace
ans o m o hem. By exp essing he cu en we can subs i u e
(1) in (2) and exp ess he ans e unc ion o he mo o (3)
whe e he ol age is he inpu and o o speed is he ou pu .
( ) 󰇗
( )
( )
( ( ) )
(3)
Knowing he nomina o and denomina o o de s o he
ans e unc ion polynomials enables he pa ame ic sys em
iden i ica ion o he sys em once a s ep inpu o 1 V has been
applied and i s esponse measu ed. Since he o a y encode
only gi es ou absolu e posi ion he angula eloci y had o be
calcula ed. To calcula e he angula eloci y an FPGA
p og am had been w i en ha uns pe iodically e e y 400 µs.
The esul s ob ained and he esul o he sys em iden i ica ion
can be seen on Fig. 5.
Fig. 5. Resul s o measu emen (blue) and sys em iden i ica ion ( ed)
The ans e unc ion om sys em iden i ica ion can be
seen in equa ion (4)
Recen Inno a ions in Mecha onics (RIiM) Vol. 3. (2016). No. 1-2.
DOI: 10.17667/ iim.2016.1-2/15.
( ) 󰇗
( )
( )
( )
(4)
To implemen he acqui ed ans e unc ion on he
mic ocon olle a bilinea ans o ma ion was pe o med wi h
he sampling equency o 100kHz o ans o m i om he s
plane o he z plane gi ing us equa ion (5) wi h he ollowing
coe icien s.
( ) 󰇗
( )
( )
( )
(5)
Using an in e se z- ans o m he di e ence equa ion was
ob ained om he disc e e ime ans e unc ion. Implemen ing
he disc e e ime ans e unc ion is a simple ma e . Since he
equa ion only con ains addi ion mul iplica ion and sub ac ion
and each o hese ope a ions only equi es 1-3 cycles o he
ARMmic ocon olle .
III. RESULTS
Fig. 6 shows a measu emen o a s ep inpu applied o he
implemen ed ha dwa e in he loop sys em in con as wi h a
pu e ma hema ical model.
Fig. 6. Resul s o s ep inpu applied o ha dwa e in he loop (squa es) and
con inuous ime sys em model ( ed)
F om he compa ison i is isible ha he wo esponsesa e
close o each o he , wi h an a e age absolu e e o o 0.88004
ad/s we concluded ha using an ARMmic ocon olle is iable
o ha d eal- ime ha dwa e in heloop simula ion. The
STM32F746ZGT6 has a 12 bi analoginpu wi h a maximum
sampling equency o 2.4 MHz husplacing he maximum
sampling equency o he bilinea ans o ma ion a 2.4 MHz,
in iple in e lea e mode hesampling equency can be boos ed
o 7.2 MHz, doing so educes he capabili ies o he
mic ocon olle o a single inpu sys em.
REFERENCES
[1] S. Len ijo, A. Mon i, E. San i, C. Welch, and R. Dougal, “A new es ing
ool o powe elec onic digi al con ol,” in P oc. IEEE PESC, Jun.
2003, ol. 1, pp. 107–111.
[2] V. Dina ahi, R. I a ani, and R. Bone , “Design o a eal- ime digi al
simula o o a D-STATCOM sys em,” IEEE T ans. Ind. Elec on., ol.
51, no. 5, pp. 1001–1008, Jun. 2004.
[3] H. Li, M. S eu e , K. Shi, S. Wood u , and D. Zhang, “De elopmen o
a uni ied design, es , and esea ch pla o m o wind ene gy sys ems
based on ha dwa e-in- he-loop eal- ime simula ion,” IEEE T ans. Ind.
Elec on., ol.53,no.4,pp.1144–1151,Jun.2006.
[4] F. Piazza, S. Squa ini, R. Toppi, M. Na a i, M. Pon illo, F. Be a elli,
and A. La anzi, “Indus y-o ien ed so wa e-based sys em o quali y
e alua ion o ehicle audio en i onmen s,” IEEE T ans. Ind. Elec on.,
ol. 53, no. 3, pp. 855–866, Jun.2006.
[5] P. Ba acos, G. Mu e e, C. Rabba h, and W. Jin, “Enabling pc-based HIL
simula ion o au omo i e applica ions,” in P oc. IEEE IEMDC, Jun.
2001, pp. 721–729.
[6] M. Pa k and I. Yu, “A no el eal- ime simula ion echnique o
pho o ol aic gene a ion sys ems using RTDS,” IEEE T ans. Ene gy
Con e s., ol.19,no.1,pp.164–169,Ma .2004.
[7] Lu, Bin, Xin Wu, He nan Figue oa, and An onello Mon i. "A low-cos
eal- ime ha dwa e-in- he-loop es ing app oach o powe elec onics
con ols." IEEE T ansac ions on Indus ial Elec onics 54, no. 2 (2007):
919-931.
[8] Sá osi J.: “Accu a e Posi ioning o Humanoid Uppe A m” In e na ional
Jou nal o Enginee ing, Annals o Facul y o Enginee ing Hunedoa a,
2011, Vol. 9, No. Ex a, ISSN 1584-2673, pp. 33-36